Problems starting Motorola SB4200 again

I have recently installed a new motherboard and CPU into my system.Due to problems with viruses etc, I flattened the harddrive and did a clean install of win xp, I also installed SP2. Now, I have a problem with the cable modem, if i re-enable the modem it automatically re-0sets itself todisable, is theis a hardware problem or a setup issue. I need help urgently please.